and other common refrigerants have boiling points above 120 K.

Discovery of superconducting materials with critical temperatures significantly above the boiling point of nitrogen has provided new interest in reliable, low-cost methods of producing high-temperature cryogenic refrigeration. The term "high temperature cryogenic" describes temperatures ranging from above the boiling point of liquid nitrogen, -195.79 °C, up to -50 °C. The discovery of superconductive properties is first attributed